PSI - Issue 33

Jamaloddin Jamali et al. / Procedia Structural Integrity 33 (2021) 832–842 Author name / Structural Integrity Procedia 00 (2019) 000–000

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Fig. 5: (a) CT fixture; (b) SENB fixture

4. Fabrication of Polymer Specimens Polyester resin was used to make the specimens for the tensile and fracture tests. The tensile test is performed to calculate the mechanical properties of polyester used in the calculation of the fracture parameters. The SENB specimen has 15x15mm cross section. To determine the fracture properties the tensile testing of the specimens required to be done according to ASTM D638 (2014). To prepare the polymer specimen, resin should be mixed with a hardener (catalyst); every kilogram of polyester resin was mixed with 10 mL of catalyst. The mixture is poured to the mold and cured in the room temperature. As for the mold, silicone rubber was used and then poured onto an initial wooden model as shown in Fig. 6. After curing, the silicone rubber mold can be utilized for multiple uses. The SENB specimen should be gently hit with a small saw and a razor to make the notched part after it is extracted from the mold. Additionally, a 1 mm crack was made by using a saw and a cutter. A different mold was made for CT specimen. Rather than using wood as the initial model, acrylic material was used, to obtain the shape and exact dimension the parts were cut by laser. Silicone rubber is then poured onto the acrylic mold to make a new mold in which the polyester can be poured in. When the silicone mold cured it became the new mold for the polyester similar to SENB and tensile specimen. After removing the CT specimen, a 1 mm crack in the tip of the notch is cut by a cutter. A drill is then used to make the two circular parts in which the pins would go through them as shown in Fig. 7 sand paper was used to smoothen the surface of all the specimens.

Fig. 6: (a) Silicone rubber mold for tensile specimen based on ASTM D638 (b) Silicone rubber mold for rectangular SENB specimen.